Air-compressor



c. F. JOHNSON. AIR COMPRESSOR.

APPLICATION FILED JULY 29. I9I9.

3 SHEE'lS-SHEEI l.

In van for Patented Sept. 28, 1920.

C. F. JOHNSON.

AIR COMPRESSOR.

APPLICATION FILED JULY 29, 19]!)- Patented Sept. 28, 1920.

3 SHEETS-SHEE'I 2.

A 7 far-r12 C. F. JOHNSON.

AIR COMPRESSOR.

APPLICATION FILED JULY 29. 1919.

1 ,354,402, PatentdSept. 28, 1920.

3 SHEE'ISSHEEI 3.

A 7" fqrnsg UNITED STATES PATENT OFFICE.

CHARLES F. JOHNSON, OF HARTFORD, CONNECTICUT.

AIR-COMPRESSOR.

Specification of Letters Patent.

Patented Sept. 28, 1920.

Application filed July 29, 1919. 'Serial No. 313,964.

To all whom it may concern:

Be it known that 1, CHARLES F. J OHNSON, a citizen of the United States, residing at Hartford, in the county of Hartford'and State of Connecticut, have invented certain new and useful Improvements in Air-Gompressors, of which the following is a specification.

This invention relates toair compressors it being of the same general type asthat disclosed by my contemporaneously-pending .application filed February 24:, 1919, Serial a motor, if water or any elastic gas under pressure passes through it, in which case the shaft would revolve in the opposite direction to'what it does when the apparatus is acting as a pressure blower, or as a vacuum pump.

Of the accompanying drawings, Figure 1 is a plan view; Fig. 2 is an elevation or section on the line 2-2 of Fig. 1; Fig. 3 is a section on the line 33 of Fig. 1; Fig. 4 is a perspective view of one of the rotating pistons with two vanes and a portion of the shaft projecting on the right. Fig. 6 shows the position of the pistons within the cylinder at starting, and the outlet and inlet ports. Fig.- 5 shows the position of the two pairs of figure-8 gears at the same instant. Fig. 7 shows the position of said gears after a quarter revolution, and Fig. 8 the position assumed by'the vanes- Figs. 9, 10, l1

and 12 show the positions assumed by the vanes and the. corresponding position of the gears on the termination of the half and three quarters of an entire revolution. .Fig. 13 shows the position of the vanes after they have moved from the original position in Fig. 5 far enough to allow the steam, in case the apparatus is used as a motor, to be confined between the vanes A and C and B and further compression and final expulsion through K and K.

The plan shows the pressure'cylinder S which is mounted on a bed plate on which are mounted the pedestals for the shaft at S, S, S and S'. The cylinder is inclosed by heads or covers as shown in Figs. 1, 2 and 3 at F. The outlet for air when working compressively is shown at G and is an overhead pipe from which two branches descend and turn to enter the cylinder on opposite sides 180 degrees apart. The left hand branch to save space is screwed into a boss cored out in the Side of the cylinder at t. The inlets for air are shown as cuts or orifices extending nearly across the cylinder at It, Figs. 1 and 3. There are two sets of them on opposite sides of the cylinder, but in Fig. 1 the second set is covered by the cylinder. 4

The pistons, one of which is shown at Fig. 4:, fit into one another and into the cylinder closely, the shafts projecting through the central opening beyond the cylinder heads. The pistons occupy the entire cylinder except a space of about degrees between the vanes, or 120 degrees in all'. The amount of this space depends on the mechanism outside, which connects them and such clearance as may be best. The ends of the vanes fit closely on the cylinder heads so as to be substantially air-tight as are the convex surfaces on the cylinder. These pistons are shown inside the cylinder by the dotted lines on Fig. 1 and on end view, Figs. 3, 13, 4, 5, 11 and 12.

They are mechanically connected as follows, to cause the vanes to approach and re cede from each other four times in a revolution. -On the shafts projecting from the cylinder heads are figure 8 gears meshing into corresponding equal gears on a shaft outside and parallel to the axis of the cylinder. These gears, well known to mechanical engineers, have in the quadrants radii of unequal lengths the sum of the lengths of a pairof corresponding radii being always the same. There are two maxima and two minima 90 degrees apart. In the gears represented, the longest radius is twice the shortest. If started in mesh on the equal radii the angular velocities will vary from equality to 2 to 1, then change back to 1 to 2, till a half revolution is made, when the variation of speed will be repeated. In the proportions stated the change of velocities results in a gain or loss to the vanes of .a

little more than 60 degrees. They will there- .fore open and shut and come into contact,

or nearly so, on the flat sides four'times in The gears on the opposite ends. of the 5 cylinder are keyed on these shafts so that the long diameter of one is parallel to the short diameter of the other, so that the gains reinforce one another. Otherwise, the gain at one end might lessen the gain at the other. In'fact, the pistons might revolve and the vanes remain at a uniform distance from each other, and the entire object of the figure 8 gears be lost. The pistons act as valves in controlling the entrance of the 'air from outside, and its expulsion when compressed. In the convex surface of the cylinder are admission ports or narrow openings extending nearly across the cylinder shown at H in Fig. 1, the corresponding ports, 180 degrees distant being hidden by the cylinder, into which a pipe to carry the air to the receiver is fitted, as shown onFig. 1 at G and on Fig. 3 at K. There should be check valves in these outlet pipes to prevent the machine from running violently backward in case the driving belt ran oif. Referring to Figs. 6 and 8, the vanes are supposed to be drivemthrough the gears by.

power a plied through the 'ulle on Fi 1. In Fig. 6 the vanes C an d D will moi e 120 degrees and the vanes B and A '60.degrees. The air in the spaces will be compressed until the front e es of the vanes A and B reach the expulslon port K and the vanes will cone together at the edge of K. Meanwhile, the space has opened degrees between A and C, which were in contact, and air has entered through the admission ports till they are covered by the advancing vane. -The space is contracted as before, and the air compressed and expelled as before, the vanes actlng to open and shut the ports at the right moment. Thus in a quarter revolution, 60 degrees by one vane and 120 degrees by the other, the two spaces occupied by air are emptied and their equivalents filled.

In a completerevolution the two open spaces will-be filled with air and the air compressed and expelled four'times. This would beequivalent to a cylinder full and one-third, less the space occupied by the central solid part'of" the vanes, or nearly "spaces, no vibration since all points arebalanced, and less weight and greater compactness of the machine.

equal to the amount delivered from the cyl- The pistons should fit the cylinder-with about 1/5000 of an inch clearance on the circumference, and the ends. For moderate pressures the leakage that would follow would be negligible, but for pressures above 15 lbs. packing strips, should be fitted thrown out either by centrifugal force or by springs. But a small leakage if confined to one side, might introduce a film of compressed air or vapor between the head and a piston on one side and force the'piston against the other head so as to cause friction. This is obviated in the following manner: The pistons are cored out as shown in the drawings, and along the flat part of the piston near the edge are-drilled three or more holes into the hollow part as shown at m, Fig. 4. Any film of air that should pass into the narrow space between the end of the piston and the head of the cylinder would strike one of these holes before it could spread, and then pass into the interior.

In the round part of the piston not far from the edges, so as to avoid the steam port, is another series of holes. Whenever any pressure is set up in the interior of the pistonit would be relieved, as these holes pass the exhaust ports also relieve any film of air or vapor that should find its way between the circumferen- These small holes would...

tial part ofthe piston and the wall of the cylinder. The amountof vapor or air so lost would be very small, and any unduethat by the inertia of rotation. As soon as .gthey open, the entrance port being toward the direction of motion, will beopened further, the-vanes will be forced apart but the forward vane will have the advantage of acting through continually increasing radii, and the vane behind 'it will have the disadvantage of acting through decreasing radii.. The forward vane will therefore act as a driving piston and the rearvane as an) abutment or moving cylinder head till the quarter revolution is made, the function of the vanes interchanged, the entrance portv again opened and rotation in the same direc- 1 tion impelled pressure on difierent faces of the vanes.

l recisely the same pperation takes place on the opposite side of the cylinder, the ports and the moving vanes being 180 degrees apart. 7'

What I claim is: '1. A device of the class described comprising a c linderwith closed ends havin two sets 0 ingress and exhaust ports I80 degrees apart, rotary pistons within the cylinder, fitting into each other and having a common axis of rotation, and means for causing the pistons to move with variable velocities and to approach and recede from each other twice in each rotation.

-2. A device of the class described comprising a cylinder provided with closed ends and having two sets of ingress and exhaust ports 18Q degrees apart, pistons within the cylinder fitting into each other and having a common axis of rotation, the pistons having shafts respectively rigid therewith, and meshing toothed elliptica gears rigid with the respective shafts and operative to cause 15 the pistons to move with variable velocitiesand to approach to and recede from each other twice in each rotation of the pistons.

In testimony whereof I aflix my signature in the presence of two witnesses.

- CHARLES F. JOHNSON. Witnesses:

ELSIE M. RABENSTEIN, HEATH SUTHERLAND. 

